Implement the SpeculationBarrier with implementations consisting of
fence instruction which provides finer-grain memory orderings.
Perform Data Barrier in RiscV: fence rw,rw
Perform Instruction Barrier in RiscV: fence.i; fence r,r
More detail is in Appendix A: RVWMO Explanatory Material in
https://github.com/riscv/riscv-isa-manual
This API is first introduced in the below commits for IA32 and x64
d9f1cac51be83d841fdc
and below the commit for ARM and AArch64 implementation
c0959b4426
This commit is to add the RiscV64 implementation which will be used by
variable service under Variable/RuntimeDxe
Cc: Andrei Warkentin <andrei.warkentin@intel.com>
Cc: Evan Chai <evan.chai@intel.com>
Cc: Sunil V L <sunilvl@ventanamicro.com>
Cc: Tuan Phan <tphan@ventanamicro.com>
Signed-off-by: Yong Li <yong.li@intel.com>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
While RISC-V hart is trapped into S-Mode, the S-Mode interrupt
CSR (SIE) is disabled by RISC-V hart. However the (SIE) is enabled
again by RestoreTPL, this causes the second S-Mode trap is triggered
by the machine mode (M-Mode)timer interrupt redirection. The SRET
instruction clear Supervisor Previous Privilege (SPP) to zero
(User mode) in the second S-Mode interrupt according to the RISC-V
spec. Above brings hart to the user mode (U-Mode) when execute
SRET in the nested S-Mode interrupt handler because SPP is set to
User Mode in the second interrupt. Afterward, system runs in U-Mode
and any accesses to S-Mode CSR causes the invalid instruction exception.
Signed-off-by: Abner Chang <abner.chang@hpe.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Daniel Schaefer <daniel.schaefer@hpe.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Signed-off-by: Abner Chang <abner.chang@hpe.com>
Acked-by: Liming Gao <liming.gao@intel.com>
